Various containers and containment means are known in the art. Many such containers and containment means require venting. The concept of venting a container or containment means is well known in the art and entails allowing gas, such as atmospheric air, to enter and/or exit the container or containment means in order to prevent extreme pressure differentials across the container structure. That is, venting is a way of stabilizing the pressure within the container and/or containment means.
For example, many containers are configured to contain a liquid product. Examples of such liquids for which containment means are used include liquid fuel, liquid ink, pesticides, fertilizer, etc. In many instances, the liquid level within a container changes over time. For example, as the liquid product is used up, the liquid level within the respective container will fall. Conversely, when the liquid product is replenished, the liquid level will rise.
Typically, such liquid containers are configured to be substantially airtight in order to prevent leakage of the liquid contents. However, due to changing liquid levels within the container, venting of the container must be provided in many instances to facilitate proper functioning of the container and related systems, as well as to prevent structural damage to the container.
As mentioned above, liquid ink is an example of the type of liquid product for which containment means are employed. Various types of liquid ink containment means are employed in the art. One example of a liquid ink containment means is an inkjet pen of an inkjet printer. Typical inkjet printers, or imaging devices, include at least one pen that is configured to cyclically traverse the width of a printable surface such as a sheet of paper.
The pen includes a print head having an array of very small printing orifices through which droplets of ink can be selectively projected, or “fired,” during movement of the pen in order to generate a desired pattern or image on the printable surface. The pen also typically includes a body that defines an enclosed ink reservoir that is configured to contain a supply of ink. Other printer formats can employ a fixed remote ink reservoir that supplies ink to a movable pen by way of a flexible tube or the like. In such cases, for the purposes of this disclosure, the remote reservoir is considered part of the pen.
Many inkjet printing systems employ pens with rigid bodies. In such cases, the ink supply reservoirs are typically vented to admit air in order to compensate for the volume of ink that is consumed during printing. Such venting prevents the development of a partial vacuum within the reservoir that can inhibit further firing of ink from the pen. In addition, such venting also allows equalization of pressure differentials caused by changes in temperature and atmospheric pressure. For example, without a vent, ambient pressure can fall below the internal reservoir pressure, thereby forcing ink out of the printing orifices, resulting in associated problems.
Conventional ink reservoirs are normally vented by way of an aperture defined in the pen body. Typically, a small cylindrical vent plug is inserted into the aperture. The plug usually has a grooved exterior surface that provides an elongated narrow air path that facilitates gradual equalization of pressure differences with respect to the reservoir. The air path provided by the groove is relatively long and narrow enough to prevent significant air exchange in an atmospherically stable environment, thereby minimizing evaporation and drying of the ink in the reservoir.
Such vent plugs are generally formed in the shape of a headless threaded machine screw having a helical, “V”-shaped groove, although other groove shapes and/or paths are known including serpentine paths and the like. For example, a vent plug having a serpentine groove path is disclosed in U.S. Pat. No. 6,273,562 to Deshmukh. A conventional vent plug is typically fabricated from a plastic-type of material such as nylon. The sharp vertices of the area between adjacent grooves are intended to crush slightly upon installation in order to provide a tight fit of the vent plug within the aperture.
While generally effective for facilitating the venting of inkjet pen reservoirs, various problems can be associated with existing vent plug configurations. For example, relatively precise alignment of the vent plug with the aperture is required for installation, and associated production difficulties are occasionally experienced, including misaligned plugs.
Similarly, such precise alignment and registration of the plug and vent aperture during installation generally requires relatively complex production machinery which often needs frequent maintenance and adjustment. Furthermore, the dimensional tolerances of the vent plug and the aperture are ideally relatively precise in order to achieve the desired press-fit of the plug. Such precise tolerances can present further associated production difficulties because of the relatively high degree of effort needed to achieve the tolerances.
Generally, a convenient way of providing a vent plug for any of a number of various liquid product containment means can be beneficial.